Over-reliance on cloud service is a critical mistake. We tend to forget that these technologies are just as prone to errors as your day to day devices. Do not save your sensitive files on the cloud.
You probably mean that it shouldn't be your only copy. Of course. But day to day devices are definitely less reliable than the redundant storage managed by a bunch of expert storage engineers.
You need to be an expert storage engineer to set up a simple, globally distributed ZFS pool feat. rsync nowadays?
Average individual does not know how to open a terminal window. :-)